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A "torque limiter" can help.
Plus, we always recommend customizing off-the-shelf cranks. They're usually designed for big burly men. And as we all know, big burly men can't hold a candle to a classroom full of third graders.
BTW-- I recall seeing a pretty solid bicycle powered generator at an alternative energy fair several years ago. Like it had been designed for the application. I kick myself for not noting the manufacturer, but the fellow standing near it said he'd ordered it online. So they're out there (or were a few years ago). Of course, again, a gaggle of youth represents so much more havoc than any grown-up looking for ways to get off-grid. Probably still better off building one from scratch with industrial parts.
: j
Jason Jay Stevens
Flutter & Wow Museum Projects
P. O. Box 21576
Detroit, MI 48221
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210.364.6305
On Mar 8, 2013, at 10:32 PM, Dan Zevin wrote:
> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related institutions.
> *****************************************************************************
>
> Greetings,
>
> We're looking for a robust yet small, lightweight hand crank generator that can withstand a lot of use by teenagers. This one gave us about 20 hours of use before the small handle snapped off: http://www.k-tor.com/hand-crank-generator/
>
> The crank needs to output at least 10W of power.
>
> If you've got suggestions for something better, we'd love to know about them!
>
> Thanks,
>
> Dan
>
> ****************************
> Dan Zevin
> Public Education Specialist
> Space Sciences Laboratory
> 7 Gauss Way, MC 7450
> University of California, Berkeley
> Berkeley, CA 94720-7450
>
> (510) 642-8326
> (510) 643-5660 [fax]
> [log in to unmask]
> http://cse.ssl.berkeley.edu
> ****************************
>
> AST:7731^29u18e3
>
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For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.
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